The present disclosure relates to a digital broadcasting system, and more particularly, to a receiver for processing vestigial sideband (VSB) signal and a processing method thereof.
Recently, broadcasting systems have been rapidly changing from analog schemes to one or more digital schemes. It is expected that digital broadcasting systems may completely replace the existing analog broadcasting systems after a few years.
Limitations in the theory and actual functionality of digital broadcasting systems and/or digital communication systems include Inter-Symbol Interference (ISI) in channels. Various channel equalization techniques have been developed for removing ISI. Such channel equalization techniques include, for example, Maximum-Likelihood Sequence Estimation (MLSE), Linear Equalization (LE) and Decision-Feedback Equalization (DFE).
In digital broadcasting systems, various channel coding and error correction techniques are used for correcting errors that occur due to noise. Particularly, in a digital television (TV) broadcasting system using an ATSC 8-VSB scheme, Reed-Solomon Code (RSC) linked with Trellis-Coded Modulation (TCM) may be used.
As an optimal scheme of decoding TCM data that is transmitted through an ISI channel where ISI exists, there is joint MLSE called Super Trellis. However, because of complexity that exponentially increases with respect to the time variable characteristics of channels, joint MLSE is recognized as not being suitable.
As the second scheme for solving such a limitation, there is a scheme that compensates ISI through a Decision Feedback Equalizer (DFE) and decodes TCM data with a Viterbi decoder. Such scheme is often used in actual works, but may have severe limitations. For TCM data received, the decision feedback equalizer that operates prior to a TCM decoder, should use an uncoded symbol for performing a feedback operation. The reliability of an uncoded symbol inputted to the decision feedback equalizer is relatively very low. Consequently, performance enhancements of the decision feedback equalizer may be limited.
In techniques of decoding TCM data, as an alternative technique that may have a small hardware burden and provide performance equivalent to that of optimal MLSE, the decision feedback equalizer and the TCM decoder (or Viterbi decoder) may be connected in cascade. However, the decision feedback equalizer references data provided from the TCM decoder instead of referencing the decision value of a decision unit (for example, a slicer). That is, the decision feedback equalizer uses a symbol decision value using the optimal survivor path of the TCM decoder. Such a scheme provides better performance than that of a scheme where the decision feedback equalizer and the TCM decoder are separately driven. This is because the decision value of the TCM decoder using the optimal survivor path has much higher reliability than that of a decision value by the slicer.
However, the developments of low-cost ATSC receivers having high performance are still urgently required for the generalization and popularization of digital broadcasting.